Electrical signaling system



July 1, 1947.

w. POUL IART ELECTRICAL SIGNALING SYSTEM Filed Jan 22, 1943 2 Sheets-Sheet l ATTORNEY I July 1, 1947. w. PO ULIART 2,423,115

ELECTRICAL SIGNALING SYSTEM Filed Jan. 22, 1943 2 Sheets-Sheet 2 7 FE] 5r INVENTOR WILL) FOUL/H97 ATTORNEY I Patented July 1, 1947 ELECTRICAL SIGNALING SYSTEM Willy Hortense Prosper Pouliart, Antwerp, Belgium, assignor to International Standard Electric Corporation, New York, N. Y., a corporation of Delaware Application January 22, 1943, Serial No. 473,275 In the Netherlands August 30, 1941 3 Claims.

The invention relates to signal transmission systems and more particularly to pulse receiving circuits.

Heretofore, in modulated carrier wave pulse receiving circuits, it has been the practice, either to impress the rectified modulated carrier Wave, through an appropriate filter and transformer, directly upon a stepping relay, or to apply the carrier wave through a suitable transformer to the grid of a hot-cathode vacuum tube, in the plate circuit of which the stepping relay is inserted.

Both these methods present certain disadvantages and one object of this invention is to provide improved modulated carrier wave pulse-receiving circuits.

According to one embodiment of the invention, the signal receiving device, adapted for receiving and reproducing modulated carrier wave pulses, comprises a filter, a transformer, a bridge rectifier, a cold-cathode tube and a number of controlling relays associated therewith, the ar rangement being such that the rectified carrier wave causes the temporary lighting of the coldcathode tube at the beginning and at the end. of each current pulse, each temporary lighting controlling the operation of the associated relays in accordance with the pulses received.

Another feature of this invention is that a first controlling relay inserted in the anode circuit of the cold-cathode tube and energized a a consequence of the lighting of this tube, causes the immediate and subsequent extinction of said tube by opening or short-circuiting of both the main and the control gap. The control anode biasing potential is, by the operating of said first controlling relay, increased to a value equal to or higher than the control gap breakdown voltage and the direction of the rectified carrier wave potential is at the same time reversed with. respect to said biasing potential, in such a man" nor that the algebraical sum of this biasin potential and the rectified carrier wave potential remains smaller than the control gap breakdown voltage, so that the cold-cathode tube is prevented from being relit during the duration ofthe pulse.

At the end of the pulse, as soon as the rectified carrier wave potential disappears, the coldcathode tube is relit by the now increased control anode biasing potential, resulting in the operation of a second controlling relay inserted in the tube anode circuit, operation of said second controlling relay causin the immediate extinction of the cold-cathode tube by opening or short-circuiting of both the main and the control gap and re-establishing the normal conditions of a state of rest in the signal receiving circuit.

Finally it is a feature of the invention that the connections to +he two control electrodes of the cold-cathode tube are changed over by the operation of the first named controlling relay in such a manner, that one control electrode is used as control anode for lighting the lamp at the beginning of the pulse, while the other control electrode is used as control anode for lighting the tube at the end of the pulse.

The invention is described by means of the drawing, in which Fig. 1 shows one embodiment of my invention using one gas discharge tube;

Fig. 2 shows another embodiment of my in vention using two gas discharge tubes;

Figs. 3, 4, 5 and 6 show various conditions which the gas discharge tube of Fig. 1 may assume during the operation of this invention.

In Fig. 1 the incoming line comprises an in ductance S1 and a capacity C1 as also the pri rnary winding of transformer T, these elements being tuned to resonance with the frequency of the alternating carrier ing.

The secondary winding of transformer 'I' is connected to a rectifying bridge R, across the output terminals of which a condenser C2 and a resistance T2 are connected. The purpose of capacity C2 is to prevent that the instantaneous value of the rectified half-waves of the incoming alternating current fall below a certain minimum value, as will be explained later, while the purpose of resistance T2 is to speed up the discharge of the condenser at the end of each pulse.

The cold-cathode tube L, referred to in this invention, is of the well known type which requires a specific control gap breakdown poten tial VX to light the control gap between the two electrodes c1 and c2 and a substantially higher main gap breakdown potential Vy to light the gap between the anode A and either of the two eletcrodes e1 and c2. Once the control gap has been lit, however, a sustaining potential V which may be considerably lower than Vy is sufiicient to maintain a current in the main gap.

It will be seen from Fig. 1 that the anode a1 is connected permanently with the negative pole of the battery, while the controlling anode as is connected to one of points P1 or P2 of potentiometer P, in series with the rectifying bridge. The anode A is connected to the positive pole of the battery in series with the relays Sr and Ar.

wave, utilized for signal- The purpose of the potentiometer is to app a certain biasing potential on the control anode, in order to increase the sensitivity of the arrangement. The purpose of resistance 1'1 is to reduce the current consumption in the control The biasing potential is smaller than the control gap breakdown voltage, so in the state of rest, the tube is not lit. This state is illustrated in Fig. 5.

In order that the following description may be more readily understood, Figs. 3, 4, 5 and 6 are now referred to. These figures represent the four conditions to which the cold-cathode tube is exposed during one pulse. Definite voltage values have been added to these figures for the purpose of clearer illustration only, so that these values are indicative only. These voltage values are in more or less correct relation to the actual working characteristics of a cold-cathode tube with a control gap breakdown voltage of '70 v.

Again referring to Fig. 1, when a pulse arrives, the rectified potential at the output terminals rectifier R will be added to the potential of point 101. The algebraical sum of the biasing potential and the rectified potential is so chosen that it ex" ceeds the control gap breakdown voltage, with the result that the control gap and subsequently the main gap, will be lit. This stage is illustrated in Fig. 3.

Relays Sr and Ar will now operate due to current flowing through the anode circuit, the former relay closing any desired circuit such as a local stepping circuit, over it right-hand front contact.

Relay Ar is slower in operation than relay Sr and its armature therefore remains still on its back contact a certain time after the armature of relay Sr has closed its lefthand front contact with the result that both the main gap and the potentiometer remain short-circuited for a time sufiicient to extinguish and de-ionize the tube. It also can be seen from Fig. 1 that relay Sr closes a holding circuit for itself, in series with relay Ar and independently of the anode circuit.

The operation of relay Ar brings about the following modifications in the condition of the various elements of the circuit:

(a) The anode A of the tube is changed over from relay Sr to relay Br. This circuit is at the moment not operative, since the tube has been extinguished by the short-circuiting action just described.

(b) Over its two left-hand change over contacts relay Ar reverses the connections between the output terminals of the rectifier and the potentiometer. The rectified alternating current potential, which originally was added to the biasing potential, is now subtracted.

(0) Over its left inner front contact relay Aiincreases the biasing potential to a higher value than the control gap breakdown Voltage. Due to the fact that the rectified alternating current potential is now subtracted, the algebraic sum of biasing and rectified potentials is lower than the control gap breakdown voltage, so that the tube remains extinguished.

This stage is represented in Fig. 4 and remains in force during the whole duration of the pulse.

At the end of the pulse, the rectified alternating current potential disappears, with the result that the increased biasing potential is re-established to its full value and the control gap is again lit. This stage is represented in Fig. 6.

The anode circuit is now established by relay Ar through the winding of relay Br, but this latter relay is slightly slow in falling off, so that the original anode circuit through the windings of relays Sr and Ar is only re-established after a certain delay. In the meantime, both the anode and the potentiometer are disconnected at the back contact of relay Br, with the result that the tube is extinguished and gets ufiicient time to become de-ionized.

One pulse has now been received and transmitted by the right front contact of relay Sr. All subsequent pulses are received in exactly the same manner as just described.

In the second embodiment of the new invention, as shown in Fig. 2, both the electrodes 61 and e2 are alternately used as control anodes. To this effect two difierent potentiometers are used and the voltage across these potentiometers is stabilized by means of the arrangement shown in the dotted rectangle of Fig. 2.

The latter arrangement comprise a cold-cathode tube Li, which is permanently lit. It is a well known property of such a tube, that the main gap sustaining voltage remains practically constant within considerable variations of the working voltage, 1. e. the voltage applied to the main gap circuit via an outside resistance.

The alternate use of electrodes er and ez as control anode reduce the wear of the cathodes and improves the conditions for de-ionization of the control gap. The use of stabilized potentiometers increases the operating limits of the circuit as an impulse receiving device.

As soon as, in Fig. 2, a pulse arrives, the rectified potential at the output terminals of rectifier R will be added to the potential of point 292 with the result that the tube will light. Electrode c2 serves as cathode and electrode 61 as control anode,

The lighting of the tube will cause the operation of the relays Sr and Ar, as previously explained, resulting in the extinction of the tube.

The operation of relay A: disconnect potentiometer P2 and connects potentiometer P1 between points t1 and tz. Electrode e1 is now connected to the negative pole of the battery and serves as cathode, while electrode e2 serves as control anode.

The rectified potential at the output terminals is now subtracted from the normal biasing potential of electrode c2 and the tube will not relight under these conditions, which persist during the whole duration of the pulse.

At the end of the pulse the rectified potential at the output terminals of R disappears with the result that the biasing potential of the electrode B2 is reestablished to its normal value, which is higher than the breakdown voltage of the control gap. The tube will, therefore, light and relay Br will be operated by the anode current.

As previously explained, the energization of relay Br will cause the extinction of the tube. by which the relays Sr and Ar release. The circuit has now reverted to the state of rest and is ready to receive subsequent pulses.

What is claimed is:

1. System of receiving and reproducing modulated carrier wave pulses, including a filter for selecting the carrier wave, transformer means fed through said filter, rectifier means fed from said transformer for developing a direct current from said waves, a cold cathode tube having a main gap and a control gap, a source of potential, biassing means including said source of potential for said control gap, a circuit including said rectifier and said biassing means for lighting said control gap at the commencement of the receipt of a pulse, a first control relay, a second control relay, a stepping relay, a circuit for said first control relay and said stepping relay including said main gap, means under the control of said first control relay for extinguishing said tube after a brief interval and for controlling said biassing means to change the bias of said control gap, means responsive to the cessation of a received pulse and including said biassing means for again closing a lighting circuit for said control gap, means responsive to the second lighting of said tube for energizing said second control relay, and means responsive to the actuation of said second control relay for again extinguishin said tube after a brief interval and for opening the circuit of said stepping relay.

2. System according to claim 1, further cornprising potentiometer biasing means and in which said first control relay includes contacts for controlling said last mentioned means to cause the biasing potential of the control gap of the tube to be increased to a value at least equal to the breakdown voltage of the control gap and for reversing the direction of the rectified carrier wave direct current output with respect to the potential of the biasing means, so that the algebraic sum of said biasing potential and the potential derived from said rectified carrier wave remains less than the breakdown voltage of said control gap, whereby the cold-cathode tube is prevented from relighting during the duration of a pulse.

' 3. System according to claim 1, in which said cold-cathode tube has two control electrodes, said source of potential comprises the steady discharge of a second cold-cathode tube, and said biasing means comprises two potentiometers, respectively connected to said two control electrodes, said first control relay being provided with contacts for alternatively connecting said potentiometers to said source, whereby said control electrodes function alternately.

WILLY HORTENSE PROSPER POULIART. 

